The current invention relates to a method for managing the production of a well, including testing, treating and controlling the production of fluids from selected intervals of a well.
Modern hydrocarbon production wells can extend several thousand meters. The longest extended reach well drilled to date has a length greater than 11 kilometers. Wells of this nature typically pass through several different types of subterranean formations. In addition to the desired hydrocarbon production zones, production wells frequently encounter brine and fresh water zones as well as in potential shale sloughing areas.
To enhance hydrocarbon production and permit subsequent well maintenance treatments, the non-hydrocarbon producing zones must be isolated from the hydrocarbon producing zones. Additionally, it may be desirable to define select production zones that are isolated from one another. For example, certain hydrocarbon production zones may produce more sand or wax than other areas. As a result, these particular zones may require frequent maintenance not necessary in the other production regions. Therefore, isolation and treatment of only the necessary zones will improve well operation economics by reducing downtime and limiting the quantity of chemicals injected downhole.
The current invention provides a method for selectively isolating regions or zones of a subterranean formation. In this method, a pre-perforated casing is placed in a wellbore penetrating the subterranean formation. Prior to placement within the wellbore, the perforations within the casing are temporarily closed or sealed by a removable sealant Following placement of the casing, the annulus between the casing and wellbore wall is filled with hardenable resincoated particulates. After setting of the resin, the resin-coated particles form a fluid permeable mass capable of filtering particles from produced fluids. Subsequently, the casing, set resincoated particles and subterranean formation are perforated by conventional perforation devices at selected locations. The newly created perforations define the regions or zones to be isolated. These perforations are filled with a curable composition, which partially penetrates the formation. Once cured, the composition forms an impermeable mass within the perforations and the areas between each impermeable mass define selected downhole zones. Following establishment of the desired zones, the removable sealant is removed from the perforations within the pre-perforated casing.
In another embodiment, the current invention provides a method for isolating zones of a subterranean formation. Regional or zonal isolation is achieved by placing a pre-perforated casing within a wellbore penetrating the subterranean formation. Prior to placing the pre-perforated casing in the wellbore, the perforations are temporarily closed or sealed with a removable sealant. Following placement of the casing, a hardenable resin-coated particulate is injected downhole and allowed to fill the annulus between the casing and the formation walls. Preferably, the hardenable resin-coated particulate sets or cures as a solid that is permeable to fluids commonly injected downhole or produced from the formation. Once set, the permeable resin is capable of filtering particles from produced fluids. Following setting of the hardenable resin-coated particulate, the casing is perforated by conventional perforation devices at intervals designed to define those zones to be isolated. The resulting perforations are filled with a curable composition, which is allowed to cure to an impermeable mass. Once the curable composition has cured, a device for isolating the region between two impermeable masses is installed in the casing. Suitable devices for isolating the desired region include straddle packers and expandable tubes or expandable well screens, encased within a fluid impermeable rubber, deformable foam or elastomer sleeve. The straddle packer is positioned such that each packer of the straddle packer is adjacent to a perforation filled with cured impermeable composition. As known to those skilled in the art, flow-through tubing joins the separate packers to form the straddle packer. Thus, once installed the straddle packer isolates the zone located between the perforations filled with the cured impermeable composition from fluid communication with the interior of the casing. In the case of an expandable tube or well screen, the device is positioned within the zone defined by two perforations filled with the cured impermeable mass and expanded to contact the interior of the casing. The combination of an impermeable sleeve and expandable tube or well screen is designed to preclude fluid communication between the formation and the interior of the casing. Following expansion, the device isolates the zone located between the perforations filled with the cured impermeable composition from fluid communication with the interior of the casing. To initiate production from the desired portions of the formation, the sealant is removed from the perforations located within the casing. The isolating device connects the producing zones and bypasses the isolated zone.